CiviCRM Community Forums (archive)

Hi, I have a donations form that was creating as a Contribution page (donation type). I have several groups and I would like the user to select what group he belongs to during completion of the donation form. I'm not allowing users to create an account neither to login to the site to check his contributions. They can submit donations via the form and they are automatically added to a specific group, the same group for all. What I really need is a way for adding an extra field to the form that will allows them to select their group from a drop down box. Does anyone knows how to achieve this functionality?